Superman's 80 year history is probably the saddest story in comics history.
Superman was created by Jerry Siegel and Joe Shuster in 1934. After being rejected numerous times, until they finally found a buyer in DC comics in 1938. They sold the rights to the character for $130, $2300 in today's money, under the promise of a cut of the royalties and continued work for their studio. DC promptly reneged, using Hollywood accounting to rob them of royalties and using other talent to make Superman.
1946, Siegel and Shuster sued DC for the rights to Superman. They lost, were promptly fired, and it's suspected by comics historians that their lawyer went behind their back and got a payment from DC to throw the case.
In 1959, with his other characters not panning out and running out of work, Siegel returned to Superman after Siegel's wife guilted DC into giving him a job. Fearing the publicity disaster should Superman's creator be found penniless and dead in the gutter, DC gave Siegel work under the stipulation that he never say he was the creator of Superman. In 1967, Siegel and Shuster filed another lawsuit to get the rights to Superman back, and lost again. Siegel's employment with DC was promptly terminated.
Siegel worked various jobs in the industry before leaving it entirely for more financially secure work at the United States Postal Service. Shuster, whose work after Superman had been largely unsuccessful, fell into partial blindness. Both men lived near the poverty line, never seeing a dime from their creation.
In 1975, DC announced the making of a Superman movie, and Siegel finally had enough. He publicly condemned it, drawing attention to how he had been mistreated by DC even though he was Superman's creator. When Jerry Robinson, himself a comic veteran who made a name for himself as a political cartoonist, and Neil Adams heard about it, they launched a massive public relation's campaign for better treatment of comic creators. Wanting to avoid bad press as much as possible, Warner Bros. bowed to public pressure and agreed to give Siegel and Shuster a yearly stipend, medical benefits, and credit their names in all future Superman stories, in exchange for no longer contesting ownership of Superman.
Superman is possibly the Ur-Example of the nightmare that is the comic book industry. It took nearly forty years for DC to credit and compensate the creators of the most successful comic book character in history, and they fought tooth and fucking nail to keep from doing it.